Nordic Congres of Clinical Neurophysiology

Nordic Congres of Clinical Neurophysiology
7-9th of May 2015
Hotel Marienlyst, Helsingør, Denmark
Webside: www.nccn2015.dk
Scientific programme
Thursday May 7th
09:00 – 17:30
Registration
10:00 – 11:00
Coffee in the exhibition area
11:00 – 11:05
Welcome
11:05 – 12:30
New neurophysiological methods in epilepsy
Chairmen;
Martin Fabricius, Department of Clinical
Neurophysiology, Rigshospitalet, Denmark
Sandor Beniczky, Department of Clinical
Neurophysiology, Filadelfia, Denmark
11:05 - 11:10 Introduction (chairmen)
11:10 – 11:30 Stereo-EEG: The Göteborg experience.
David Krýsl, Sahlgrenska University Hospital,
Gothenburg, Sweden.
11:30 - 11:45 EEG – source imaging in Epilepsy.
Göran Lantz, Neurology Clinic, University Hospital,
Geneva, Switzerland and Lund University Hospital,
Sweden
11:45 - 12:00 MEG – source imaging.
Sandor Beniczky, Department of Clinical
Neurophysiology, Filadelfia, Denmark
12:00 - 12:10 Source imaging, discussion.
12:10 - 12:30 ContinuousEEG.
Martin Fabricius, Department of Clinical
Neurophysiology, Rigshospitalet, Denmark
12:30 – 14:00
Lunch, coffee in the exhibition area and poster session
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14:00 – 15:30
Channelopathies and neurophysiological investigations
Chairman;
Christian Krarup, Department of Clinical
Neurophysiology, Rigshospitalet, Denmark.
14:00 - 14:30 Channelopathies in peripheral nerve.
Christian Krarup, Department of Clinical
Neurophysiology, Rigshospitalet, Denmark
14:30 - 15:00 Channelopathies in muscle.
Werner Z’Graggen, Universitätsklinik für
Neurochirurgie, Bern Universty Hospital,
Switzerland
15:00 - 15:30 Channelopathies in pain.
Kristin Ørstavik, Section of Clinical
Neurophysiology,
department of neurology, Oslo University Hospital,
Norway
15:30 – 16:00
Coffee in exhibition area
16:00 – 17:30
Free communications
17:45
Meet in the hotel lobby
18:00
Welcome reception at Kronborg with guided walk.
Friday May 8th
08:30 – 17:00
Registration
09:00 – 10:00
Keynote lecture; Single fiber EMG – historical landmarks and
present developments.
Erik Stålberg, Institute of Neuroscience, Clinical Neurophysiology,
Uppsala, Sweden
10:00 – 10:20
Coffee in exhibition area
10:20 – 11:50
Neuromuscular investigation in the critically ill patient
Chairman;
Clarissa Crone, department of Clinical
Neurophysiology, Rigshospitalet, Denmark.
10:20 - 10:50 Critical illness myopathy/polyneuropathy:
Pathophysiology and diagnostic procedures during
early course and follow up
Susanne Koch, Department of Anesthesiology and
Intensive Care Medicine, Charité Campus VirchowKlinikum, Berlin, Germany.
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10:50 - 11:20 Bench to bedside project on intensive care unit
muscle wasting: Underlying mechanisms and specific
interventions.
Lars Larsson, Department of Physiology &
Pharmacology, Dept. of Clinical Neuroscience,
Karolinska Institute, Sweden
11:20 - 11:50 Optimizing testing methods and collection of
reference data for differentiating critical illness
polyneuropathy from critical illness myopathy:
Humberto Skott, Department of Physiology &
Pharmacology, Dept. of Clinical Neuroscience,
Karolinska Institute, Sweden
11:50 – 13:10
Lunch, coffee in the exhibition area and poster session
13:10 – 14:30
Neurophysiological methods for intraoperative monitoring
Chairman;
Birger Johnsen, Department of Clinical
Neurophysiology, Aarhus University Hospital,
Denmark.
13:10 - 13:30 IOM in glioma surgery:
Hans Axelson, Department of Clinical
Neurophysiology, Uppsala University Hospital,
Sweden
13:30 - 13:50 IOM in brainstem surgery:
Pål Gunnar Larsson, Division of Surgery and Clinical
Neuroscience, Oslo University Hospital, Norway
13:50 - 14:10 Intraoperative neurophysiology in intraspinal surgery:
Jonas Persson, Department of Clinical
Neurophysiology, Karolinska University Hospital,
Stockholm,Sweden
14:10 - 14:30 Intraoperative monitoring of scoliosis surgery.
Ralf-Peter Michler, Department of Clinical
Neurophysiology, St. Olav’s Hospital, University
Hospital of Trondheim, Norway
14:30 – 15:00
Coffee in exhibition area
15:00 – 16:00
Nerve and muscle Ultrasound and MRI
Chairmen;
Erisela Qerama Montvilas, Department of Clinical
Neurophysiology, Aarhus University
Hospital,Denmark
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Nils Wolfram, Department of Clinical
Neurophysiology, Glostrup, Denmark
15:00 - 15:20 What can you see on neuromuscular imaging?
Michel Court Payen, Gildhøj Private Hospital,
Denmark
15:20 - 15:40 Nerve and muscle ultrasound in neuromuscular
disorders - Experiences and results of prospective
studies:
Erisela Qerama Montvilas, Department of Clinical
Neurophysiology, Aarhus University
Hospital, Denmark
15:40 - 16:00 Experiences of combined electrophysiology and
High Resolution UltraSound in the examination of
peripheral nerves:
Nils Wolfram and Janus Kaufmann, Department of
Clinical neurophysiology, Glostrup, Denmark
16:00 – 17:00
Parallel hands-on sessions:
1) Neuromuscular ultrasound.
Nils Wolfram, Erisela Qerama
2) Threshold tracking in channelopathies.
M. Moldovan, W. Z’Graggen, H. Tankisi
19:00
Gala dinner
Saturday May 9th
08:30 – 11:00
Registration
09:00 – 10:00
Keynote lecture; Brain basis of social interaction.
Riitta Hari, Brain Research Unit, Aalto University, Finland
10:00 – 10:30
Coffee in exhibition area
10:30 – 12:30
Neurophysiological methods in sleep and aging
Chairman;
Benedikte Wanscher, Department of Clinical
Neurophysiology, Glostrup, Denmark
10:30 - 10:45 REM sleep Behaviour Disorder: An early sleep disease
marker for late neurodedeneration.
Poul Jennum, Department of Clinical
Neurophysiology, Glostrup, Denmark
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10:45 - 11:00 Electromyographic activity in REM sleep behavior
disorder.
Rune Frandsen, Department of Clinical
Neurophysiology, Glostrup, Denmark
11:00 - 11:15 Prepulse inhibition is associated with attention,
processing speed, and 123I-FP-CIT SPECT in
Parkinson’s disease.
Marielle Zoetmulder, Department of Clinical
Neurophysiology, Glostrup, Denmark Denmark
11:15 - 11:30 Sleep stability and transitions in patients with
idiopathic REM sleep behaviour disorder and patients
with Parkinson ’s disease.
Julie AE Christensen, Department of Clinical
Neurophysiology, Glostrup, Denmark
11:30 - 11:45 The Copenhagen longitudinal study of male cognitive
aging and fMRI and EEG measures of cognitive
decline.
Martin Lauritzen, Department of Clinical
Neurophysiology, Glostrup, Denmark
11:45 - 12:00 Selective attention modules auditory and visual
steady state responses.
Krisztina Benedek, Department of Clinical
Neurophysiology, Glostrup, Denmark
12:00 - 12:15 Neurophysiological correlates of illusions: Visual
perceptive network study.
Anna Horwitz, Department of Clinical
Neurophysiology, Glostrup, Denmark
12:15 – 12:30 Neocortical gamma oscillations in epilepsy.
Krisztina Benedek, Department of Clinical
Neurophysiology, Glostrup, Denmark
12:30
Sandwiches in exhibition area and goodbye
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Stereo-EEG: the Göteborg experience
David Krysl, Bertil Rydenhag, Kristina Malmgren
Sahlgrenska University Hospital, Göteborg, Sweden
Introduction: Stereoencephalography (SEEG) uses stereotactically implanted intracerebral electrodes
to test hypotheses about origin and propagation of epileptic seizures. It allows exploration of deep
cortical regions and reconstruction of seizure pattern in 3D. SEEG candidates are commonly MRnegative or have electroclinical syndrome discordant with lesion location. In Göteborg, SEEG was first
performed in 2013/04 and is now important part of epilepsy surgery program.
Methods: Review of approach to SEEG in Göteborg and presentation of patients investigated by SEEG
since 2013/04.
Results: 6 adults (age 20-40) and 4 children (age 4-9) underwent SEEG. 4 adults presented as TLE with
concerns about extent of epileptogenic zone or multilobar (fronto-temporal) involvement. Two adults
presented as frontal lobe epilepsy (FLE), one was later reclassified as possible medial parietal case.
One child presented as TLE+ (TPO), and 3 as FLE. SEEG was well tolerated, no major complications
were observed. Minor complications (without deficits) included one epidural hematoma caused by
orthogonal frontoorbital electrode and one bleeding during electrode insertion. Reduction in number of
electrodes due to poor bone quality was unexpectedly needed in the youngest child. SEEG lead to
cortical resection in 3/4 children and 4/6 adults. All three operated children and 3/4 adults are
seizure-free post-op (follow-up 0,5-1 year).
Conclusions: SEEG is an effective and relatively safe method for investigating complicated patients
with refractory focal epilepsy. Its successful use is heavily dependent on the comprehensiveness of preimplantation hypotheses. Its use is not limited to adults, but it may be technically difficult in small
children. Given the complexity of patients referred for SEEG, short-term seizure freedom in 6/7
operated patients is encouraging. SEEG may also bring evidence in favor of conservative approach that
helps to avoid unsuccessful attempts at resective surgery.
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EEG Source Imaging in Epilepsy
Göran Lantz, Electrical Geodesic Inc, Eugene OR, USA
In presurgical investigations of patients with pharmaco-resistant epilepsy different non-invasive
investigations are performed before proceeding to either invasive recordings or directly to surgery.
Among the different non-invasive techniques for localizing the epileptic focus are the electromagnetic
methods (based on EEG or MEG recordings) and the hemodynamic methods (PET,SPECT,fMRI). These
classes of investigations are complementary in the sense that the electromagnetic methods have a
better temporal resolution (down to a few milliseconds) whereas the hemodynamic methods (notably
fMRI) have a better spatial resolution. One such non-invasive technique for localizing the epileptic
focus is Electrical Source Imaging (ESI). This technique is used to 3-dimensionally localize the source of
interictal epileptiform activity from high density EEG recordings.
In this presentation a workflow for the ESI investigations will be suggested. The importance of using a
sufficient number of recording electrodes as well as the importance of which timepoint of the spike is
chosen for the analysis will be demonstrated. Different evaluation studies demonstrating the usefulness
of the technique will be presented and the possibility to combine ESI with other non-invasive
neuroimaging techniques will be discussed.
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MEG – source imaging
Sandor Beniczky (Danish Epilepsy Centre and Aarhus University)
Several strategies are available for solving the inverse solution: determining the location in the brain of
the cortical areas generating EEG and/or MEG signals. This presentation reviews the principles behind
the various source imaging strategies and reviews the published evidence for the diagnostic accuracy
and clinical utility.
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cEEG
Martin Fabricius, dep.of Clinical Neurophysiology, Rigshospitalet, Copenhagen.
Continuous EEG (cEEG) is a key instrument for diagnosing and treating non-convulcive seizures and nonconvulsive status epilepticus. Furthermore non-epileptic motor manifestasions are common in
unconscious patients in the intensive care unit and may be distinguished from true seizures by means of
cEEG. The analysis requires a considerable man-power from trained EEG-interpreters, but may be
performed on-line by remote-access. The cEEG trace is evaluated by direct inspection as well as by
means of quantitative EEG measures such as amplitude integrated EEG and power spectrum trend
analysis. Bedside staff must be trained to enter events into the EEG software such as changes in
medication and clinical events, to allow an optimal assessment. Current dialogue with the attending
neurologists and intensivists is very important. Recordings will be presented to demonstrate typical
cases as well as pitfalls.
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Channelopathies in peripheral nerve
Christian Krarup, Department of Clinical Neurophysiology, Rigshospitalet and University of Copenhagen,
Denmark
Nerve fibre function is dependent on the concerted activation and inactivation of a number of ionchannels integrated in the axolemma. In myelinated fibres, the different channels are segregated at
the node of Ranvier and at the internode. The homeostasis of ion concentrations is furthermore
dependent on various ion pumps and exchangers that maintain the axon membrane potential.
Abnormalities of ion channels and pump function may cause cramps, paraesthesia, pain, sensory loss or
weakness and may eventually lead to nerve fibre degeneration.
Channelopathies may be hereditary or acquired. Hereditary channelopathies may affect Na + or K+
channels and include symptoms localized to the peripheral or the central nervous system or both.
Acquired disorders that affect ion channels directly by blocking or indirectly through metabolic changes
are more common, as for example autoimmune blocking of K +-channels in motor fibres. Furthermore,
changes in ion-channel distribution may have functional implications in for example chronic
demyelinating neuropathies and in regenerated fibres. Studies in hereditary motor and sensory
neuropathies have also shown that aberrant ion-channels, usually not present at the node of Ranvier,
may become expressed, and such ectopic channels may cause disturbed function confirming that
transcriptional changes may lead to channelopathies.
Conventional nerve conduction studies are not well suited to unravel changes in function associated
with ion-channel or axon membrane dysfunction. NCS may show loss or slowing of fibres but
complementary studies of axonal excitability have become increasingly useful in the understanding of
dysfunction of nerve fibres that are still able to conduct action potentials. These methods use
threshold tracking to assess changes in membrane potential and thus gain insight into ion-channel
functions. By combining different conditioning potential changes, the accommodation associated with
activation of ion-channels localized at the node of Ranvier and at the internode can be assessed.
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Channelopathies in muscle
Werner Z’Graggen, Departments of Neurology and Neurosurgery, University Hospital, Bern, Switzerland
Muscle fibers, like nerve fibers, are complex electrical organs, in which the accurate control of
membrane potential, and the interplay of multiple voltage-dependent ion channels, have essential
roles in normal physiological function. The number and diversity of diseases of striated muscle greatly
exceeds the number of symptoms and signs by which they express themselves clinically; thus, different
diseases share certain common symptoms. The typical diagnostic sequence in a patient with suspected
myopathy consists of taking patient history, clinical examination, laboratory investigation and needle
electromyography followed by muscle biopsy or genetic testing. Clinical and laboratory examinations
provide often rather unspecific findings. Also qualitative and quantitative electromyography have a
limited sensitivity to reveal the cause of myopathy or to characterize the type of channelopathy.
We have developed a method of recording muscle velocity recovery cycles, with the aim of facilitating
the diagnostic process in patients with suspected myopathy. A muscle action potential is followed by
early and late depolarizing afterpotentials, which can be assessed by their effects on the conduction
velocity of a second muscle action potential. After the refractory period, the early afterpotential gives
rise to an increase in velocity (early supernormality), which is highly sensitive to the muscle resting
potential. The late afterpotential is augmented by multiple conditioning stimuli and thought to reflect
potassium accumulation in the t-tubules.
Muscle velocity recovery cycles provide the clinical neurophysiologist with a quick and virtually painless
method of obtaining information about human muscle membrane properties in vivo. Recently, the
method has been used to demonstrate distinct changes in different myopathies including
channelopathies. For example it has been shown, that chloride channel dysfunction causes
characteristic alterations in muscle velocity recovery cycles in myotonia congenita and the myotonic
dystrophies.
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Channelopathies and pain.
Kristin Ørstavik, MD, PhD. Section of Clinical Neurophysiology, Department of Neurology, Oslo
University Hospital
Ion-channels are crucial for conveying pain sensation in the peripheral and central nervous system. In
later years the research regarding the role of ion-channels in chronic pain has been intensified. Our
knowledge of possible mechanisms for neuropathic pain has been broadened due to the discovery of
certain hereditary sodium-channel mutations that leads to rare chronic pain conditions such as primary
erythromelalgia, while other mutations leads to an insensitivity for pain. Even in some patients with
presumed idiopathic polyneuropathy, mutations of sodium-channels with a possible critical role in the
generation and conduction of action potentials in nociceptors have been reported.
In primary erythromelalgia patients, multiple different mutations have been identified in the gene
coding for the voltage gated sodium channel subtype 1.7 (Nav1.7). Experimental animal studies have
among other findings shown that this leads to hyperexcitability of nociceptors. Direct
microneurographic recordings from small nerve- fibers has enabled us to study axonal properties of
nociceptors in healthy subjects and how these may change in patients with painful disorders. Cnociceptors in healthy humans show a characteristic activity-dependent slowing of conduction velocity.
The observation of a changed pattern of such activity-dependant slowing could reflect one aspect of
the underlying ion-channel pathology in primary erythromelalgia. The analyses of mechanisms in such
rare disorders might help us understand more about pathological pain including the role of ion-channel
pathology.
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SFEMG - historical landmarks and present developments
Erik Stålberg, Dept Clin Neurophysiology, University Hospital Uppsala Sweden
In late 50ties Ekstedt and myself started at the Department of Pharmacology Uppsala University for a
PhD thesis and the topic given to us was on muscle fatigue. We started with strain gauges, integrated
surface EMG recordings, ischemia and so on. In order to get more information from the muscle we
looked for other electrophysiological recording parameters and were inspired by Buchthal´s
multielectrode. We used some of those, but thought that smaller recording surfaces perhaps could
reveal more details. After lots of testing, SFEMG electrodes were constructed by ourselves containing
1-14 very small recording surfaces, each with a size smaller than the muscle fiber. The obtained signals
caused considerable headache. Which is the generator, can it be just ONE muscle fiber? This was
against the prevailing concept of organization of muscle fibers within the motor unit (MU) in small
bundles of fibers of 10-30 fibers, a subunit. We tested to see if our signals were generated by many or
just one muscle fiber by using small multielectrodes to study volume conduction, injected sodium
citrate intramuscularly to activate individual muscle fibers, induced slight curarization that supposedly
should have caused a disintegration of the signal if composed of many fibers, and made recordings in
MG, where single fiber signals should block together in an all-or-none fashion. The conclusion after
some years, that included a couple of consultations with Buchthal in Copenhagen who was our primary
opponent, was that the signals really come from individual fibers.1 Another conclusion was that the
organization of muscle fibers in a MU are arranged randomly, across the MU territory. During this work
two separate phenomena were described. First the jitter phenomenon, which is a variability in
transmission time in individual motor endplates. Its physiology was supported by intracellular recording
by Elmquist and Quastel. The jitter phenomenon was closely studied both with voluntary and electrical
stimulation regarding physiology (the effect of temperature, long term activity, response to drugs,
ischemia, anesthetic agents) and methods for quantitation. After some time the jitter was introduced
as a routine method more or less universally for the diagnosis of MG.
The other parameter of the single muscle fiber was its propagation velocity.2 This varied from one
discharge to the other depending on activity during the immediately preceding 1000 ms. This variability
was due to the “velocity recovery function” (VRF), which followed a very strict mathematical law and
was interpreted to be an ion channel phenomenon. This has recently been taken up for further
excitability studies by Bostok et al. In addition the velocity decreased during continuous activity. With
SFEMG recordings we also looked at the local organization of muscle fibers in a given MU, called “Fiber
Density” (FD). This is abnormal in reinnervation but also in some myopathies.
During the development and later clinical implementation of SFEMG, computer techniques have been
essential for practical application of jitter analysis, which actually was the first application of
computers in EMG. Initially we had a film camera in front of a time interval counter showing numbers,
and each sweep triggered a frame in the camera. All data were then inserted manually on punch cards,
which were processed in the university computer, (IBM 1640, 16 Kb). Later, time measurements were
made with PCs, and today all EMG manufacturers have implemented software for jitter analysis.
Over the years a number of nerve-muscle disorders have been explored with SFEMG3 and many
observations have explained what we see in conventional EMG (jitter, VRF, change in propagation
velocity with fatigue).
With more strict rules regarding the use of disposable material in medicine, including EMG electrodes
in some countries, we have been forced to find a replacement for the SFEMG electrode to measure
jitter. After practical and theoretical testing we have found the smallest available “facial” concentric
needle electrode to be a workable alternative for jitter measurements, but not for fiber density. A
multicenter study to obtain new reference values has just been completed. The jitter is somewhat
lower in this reference material than the previously developed reference limits for SFEMG, however the
diagnostic sensitivity for MG has been shown to be similar to that of SFEMG.
SFEMG has also been applied to study not only neuromuscular transmission but also the jitter in single
anterior horn cells in vivo (via the H-reflex), F-responses, multisynaptic reflexes (blink & flexion
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reflexes) and central transmission during cortical stimulation. A phenomenon called the “axon reflex”
has been used to study the terminal motor nerve branches using electrical stimulation.
The so-called “Complex Repetitive Discharges” (CRD) have been explained from SFEMG studies as a sign
of hyperexcitability with ephaptic transmission between muscle fibers.
In summary, jitter measured by SFEMG is an established clinical technique, which so far is the most
sensitive electrophysiological parameter to detect disturbed n-m transmission in vivo. It should be
stressed, however, that increased jitter is a sign of disturbed transmission at the neuromuscular
junction, which is not specific for MG, since jitter is seen in early reinnervation, during ischemia, and
probably during electrolyte disturbances and other conditions. SFEMG has also helped understand a
number of phenomena seen in conventional EMG and is a valuable tool to study single cell activity
elsewhere than in the muscle fiber.
Improved technical facilities in EMG equipment have made the technical part easier, but SFEMG still
requires special skill of the operator.
Reference List
1.
Ekstedt, J. and Stålberg, E. A method of recording extracellular action potentials of single
muscle fibres and measuring their propagation velocity in voluntarily activated human muscle.
Abstracts of Communications , 82-84. 1963.
2.
Stålberg E. Propagation velocity in single human muscle fibres. Acta Physiologica Scandinavica
1966; suppl 287:1-112.
3.
2010.
Stålberg E, Trontelj JV, Sanders DB. Single Fiber EMG. Uppsala: Edshagen Publishing House;
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Critical illness myopathy / Critical illness polyneuropathy: pathophysiology and diagnostic
procedures during early course and follow up
Susanne Koch, Department of Anesthesiology and Intensive Care Medicine, Charité Campus VirchowKlinikum, Berlin
Objective: Neuromuscular dysfunction in critically ill patients is attributed to either critical illness
myopathy (CIM) or critical illness polyneuropathy (CIP). We investigated the impact of early,
electrophysiological, differential diagnostic on clinical prognosis. Immobilization, systemic
inflammation and impaired glucose metabolism are major risk factors, but the underlying
pathophysiology is uncertain.
Methods: Critical ill patients (Sequential Organ Failure Assessment score > 8 on 3 consecutive days
within 5 days in ICU) were investigated: Elektrophysiological studies including direct muscle stimulation
and threshold tracking; successive muscle biopsies to assess histology, glucose metabolism and
inflammation response. Unilateral electrical muscle stimulation was performed.
Main Results: CIM is more frequent; CIP protracts ICU discharge and hampers complete recovery.
Nonexcitable muscle membrane predicts muscle weakness, showing preferential type II fiber atrophy.
Decreased synthesis and increased degradation of myosin heavy chain was found in CIM. Failing Glucose
transporter-4 (GLUT-4) translocation to the sarcolemmal membrane has been proved in CIM and cannot
be aboslished by insulin treatment, whereas electrical muscle stimulation increased repositioning of
GLUT-4. Interestingly, skeletal muscle contributes to general inflammation, showing up-regulated
serum amyloid A1 expression. Membrane depolarization of motor nerves is a general feature of
critically ill patients, whereas CIM/CIP patients show reduced membrane excitability and a
“paradoxical” reduced potassium current over the membrane.
Conclusion: Our studies shed light on the pathophysiology of CIM / CIP, describing the central role of
membrane inexcitability, immobilization, glucose metabolism and systemic inflammation.
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Bench to Bedside Project on the Intensive Care Unit Muscle wasting: Underlying Mechanisms and
Specific Interventions
Lars Larsson ([email protected]), Department of Physiology and Pharmacology, Department of
Neuroscience, Clinical Neurophysiology, Karolinska Institutet, Stockholm, Sweden
Objective. Impaired muscle function accompanies intensive care unit (ICU) patients with negative
consequences for recovery from primary disease and weaning from the respirator. Accordingly, there is
urgent demand for novel treatments and preventive measures, requiring research on the underlying
mechanisms. This project is focused on the acquired critical illness myopathy (CIM) and the ventilator
induced diaphragm muscle dysfunction (VIDD). Novel experimental models and methods for analyses of
muscle tissue have been used, giving us an unprecedented opportunity to (a) address the causative
factors and underlying mechanisms, and (b) develop effective treatments.
Methods. Novel experimental ICU (ExICU) models together with analyses of muscle tissue from ICU
patients have been used to study the mechanisms underlying the muscle wasting and impaired function
of limb, respiratory and craniofacial muscles in time-resolved studies. Gene/protein expression,
protein-protein interactions, mitochondria structure/function and regulation of muscle contraction at
the muscle fiber level have been analyzed.
Results. Long-term exposure to immobilization and mechanical ventilation in the rat ExICU model
induced an identical muscle geno/phenotype as in ICU patients with CIM, suggesting that the complete
mechanical silencing unique for ICU patients is an important factor underlying CIM. Mild passive
mechanical loading reduced the decrease in muscle fiber function in both experimental and clinical
studies, supporting early physical therapy in immobilized and mechanically ventilated ICU patients.
Pharmacological intervention with a chaperone co-inducer had strong positive effects on mitochondria
and muscle fiber function in the diaphragm, providing proof-of-concept for the translation of this
intervention to clinical studies.
Conclusion. Specific mechanisms and muscle type specific differences have been unravelled and
positive outcomes of specific interventions have been documented. This will facilitate the translation
of laboratory findings into practical clinical knowledge; leading to useful therapies and improved
outcomes for patients in need of mechanical ventilation and critical care.We have studied the
combined effects of controlled mechanical ventilation (CMV) and ageing on diaphragm muscle single
fibres using a unique rat model simulating Intensive Care Unit (ICU) conditions and the effects of
chaperone co-inducer (BGP-15).
Methods: The effects of 5 days CMV on diaphragm muscle fibre size and function were investigated in
young and old F344 Brown Norway hybrid rats. The experimental groups were deeply sedated,
pharmacologically paralyzed and extensively monitored 24 hours per day. BGP-15 was given in
systemically by intravenous infusion. After 5 days, the mid-costal parts of the diaphragm were
dissected, chemically skinned and prepared for contractile measurements. Cross sectional area (CSA)
absolute force (P0) and specific force (absolute force/CSA) were measured at the single muscle fibre
level.
Results: An ageing-related hypertrophy and decline in specific force were observed in control fibres. A
compensatory hypertrophy was observed in response to 5 days CMV in both young and old animals.
Systemic administration BGP-15 had a significant positive effect on diaphragm muscle fibre specific
force in the young, restoring it to control values, but not in the old. The strong effect of BGP-15 on
muscle fibre function in the young was paralleled by a significant up-regulation of HSP 70, but this
effect was absent in the old.
Conclusions: Significant age-specific differences were observed in control diaphragm fibres and in the
response to 5 days CMV. Further, BGP-15 had a strong positive effect on diaphragm muscle fibre
function and HSP expression after 5 days CMV, but this effect was restricted to the young animals.
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Optimizing testing methods and collection of reference data for differentiating critical illness
polyneuropathy from critical illness myopathy
Humberto Skott, MD, Karolinska Universitetssjukhuset, Huddinge, Neurofysologiska Kliniken C1-78
141 86 Stockholm, Sweden
INTRODUCTION: Acquired muscle weakness in critically ill patients in the ICU is a major cause of
morbidity and mortality. In severe acute quadriplegic myopathy, muscle fibers are electrically
inexcitable; in critical illness polyneuropathy the excitability remains normal. Conventional
electrodiagnostic methods do not provide the means to adequately differentiate these.
OBJECTIVE: To further optimize methodology for the study of critically ill ICU patients and to create a
reference value database in healthy controls.
METHODS: Different electrophysiologic protocols were tested to find techniques as robust as possible
and with sufficiently reproducible results for clinical diagnostic applications.
RESULTS: Many parameters show large test - retest variability within the same healthy subject.
Reference values have been collected and described as a basis for studies of weakness in critical
illness.
DISCUSSION: With these parameters described and quantified, we can now apply these to actual
patients with weakness in the setting of critical illness.
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IOM in glioma surgery
Hans Axelson
The main goal of glioma surgery is to achieve maximal cytoreduction while obtaining optimal functional
outcome. For this purpose, there is an increasing demand for intraoperative neurophysiology (ION) in
addition to other assistive pre- and intraoperative technologies. Like any other diagnostic tool, ION
may produce false positive “alarms”, with the risk of reducing the extent of resection and long-term
survival. On the other hand, false negative results may instill a false sense of security which may lead
to permanent neurological deficits from the surgery. Obviously, all attempt should be made to use
standardized ION techniques while bearing in mind the lack of “high-evidence” support for some of the
procedures.
In this presentation, I will describe some of the established ION methods used in glioma surgery and
share some of our experience in this context. Basically, the ION procedures are divided into mapping
and monitoring techniques. Cortical mapping is the first step where the neurophysiologist aid the
surgeon to find a suitable cortical entry point for tumour resection by excluding that “eloquent”
cortical areas is in the harm’s way. For tumours near the primary motor cortex it may be sufficient to
establish the location of the central sulcus by phase-reversal SEP whereas planned surgery near or
within cortical language regions requires electrical stimulation of those regions in the awake patient.
As tumour resection proceeds, it is important to continuously control the integrity of cortical areas and
their subcortical projections with for instance MEP monitoring from contralateral muscles. In the awake
patient, the functional status is typically monitored by clinical motor-, language- or cognitive tests in
addition to some of the standard ION monitor procedures. Not to forget, is that subcortical pathways
can be located by electrical stimulation in the resection cavity (subcortical mapping) which may
produce a “no-go” result for further resection.
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IOM in brainstem surgery:
Pål Gunnar Larsson, Dr. philos., Seksjonsleder Klinisk nevrofysiologi, Nevrokirurgisk avdeling, Oslo
Universitetssykehus
The human brainstem is very complex and this makes neurosurgery in the area difficult. Due to the
compact nature and the complex organization it may be difficult for the neurosurgeon to navigate and
to avoid damage to the locale structures. To monitor and to help localizing structures, a set of clinical
neurophysiological methods are available. The cranial nerves leave the central nervous system in the
brainstem area. Except the Olifactory Nerve, there are clinically available methods for monitoring all
cranial nerves. The optical nerves may be monitored by continuous flash-VEP and acoustical nerve by
AER. The other cranial nerves may be monitored by means of spontaneous EMG recording, and most of
them may also be localized by stimulation procedures e.g. needed when the nerve roots are embedded
in tumor tissue. Passing nerve tracts may be monitored both by SEP, MEP and direct stimulations. MEP
may even be used on the cranial nerves, but there are challenges. Available methods and challenges
will be discussed and practical experiences will be conveyed.
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19
Intraoperative neurophysiology in intraspinal surgery
Jonas Persson, [email protected]
During surgical procedures in the spinal canal there is a potential risk for damage to the spinal cord or
nerve roots which could result in postoperative neurologic dysfunction. To prevent or minimize this
hazard, various electrophysiological techniques are used intraoperatively.
For monitoring of spinal cord motor function, motor evoked potentials (MEPs) are generated by
transcranial electrical stimulation over the motor cortex and recorded from appropriate muscles
(muscle MEPs, mMEPs) or asynaptically from the corticospinal tracts (direct wave, D-wave). Recording
of mMEPs are often used in combination with D-wave recording to enable a graded evaluation of the
motor function integrity.
To evaluate the functional integrity of the lemniscal sensory pathway, which is of outermost
importance in spinal cord surgery during e.g. posterior myelotomy, somatosensory evoked potentials
(SEPs) are recorded transcranially over the sensory cortex following electrical stimulation of peripheral
nerves (tibial nerves most often used in lower limbs and median or ulnar nerves in upper limbs). If the
dorsal median raphé of the spinal cord is difficult to identify by anatomical landmarks, SEPs from the
lower limbs can be recorded selectivley from the gracile fasciuli for identification of the physiological
dorsal midline of the spinal cord.
In addition to spinal cord surgery there are surgical procedures in the spinal canal at the level of conus
medullaris/cauda equina where electrophysiological monitoring and mapping can be used. Recording of
free-running EMG during surgical manipulation and recording of compound muscle action potentials
(CMAPs) during fokal electrical stimulation of various structures in the operative field are done from
relevant myotomes for identification of nerve root elements.
Monitoring of genitourinary and anorectal functions (by e.g. pudendal SEPs, bulbocavernosus reflex)
could also be of importance during surgery in this area.
References:
Vodušek D.B. and Deletis V. (2008) Sacral roots and nerves, and monitoring for neuro-urologic
procedures. In: Handbook of Clinical Neurophysiology. Volume 8, Intraoperative Monitoring of Neural
Function. M.R. Nuwer, ed. Elsevier, Amsterdam, pp. 423-433.
Sala F. and Kothbauer K.F. (2008) Intraoperative neurophysiological monitoring during surgery for
intramedullary spinal cord tumors. In: Handbook of Clinical Neurophysiology. Volume 8, Intraoperative
Monitoring of Neural Function. M.R. Nuwer, ed. Elsevier, Amsterdam, pp. 632-650.
Husain A.M. (2008) Surgery for thethered cord syndrome and other cauda equina lesions. In: Handbook
of Clinical Neurophysiology. Volume 8, Intraoperative Monitoring of Neural Function. M.R. Nuwer, ed.
Elsevier, Amsterdam, pp. 689-699.
Rodi Z and Vodušek D.B. (2008) Monitoring of neural structures involved in micturition and sexual
function. In: Handbook of Clinical Neurophysiology. Volume 8, Intraoperative Monitoring of Neural
Function. M.R. Nuwer, ed. Elsevier, Amsterdam, pp. 739-747.
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20
Intraoperative Monitoring of Scoliosis Surgery
Ralf Peter Michler,St.Olavs Hospital Trondheim
The Scoliosis Research Society defines scoliosis as a lateral deviation of the normal vertical line of the
spine by at least 10 degrees. There are three categories; congenital, neuromuscular and idiopathic
scoliosis. The most commen, form idiopathic scoliosis, is present in 2% to 4% of children older than 10
years. Surgical intervention is indicated in patients where the curvature is over 40-50 degree.
Neurologic impairment, particularly paraparesis or paraplegia are infrequent but potentially devasting
complications of scoliosis surgery. The survey of 7885 scoliosis surgeries showed that spinal cord injurie
occurred with a frequency of 0,72%. ( Scoliosis research society 1975).
The greatest risk of spinal cord injury occurs during distraction of the spine, and injury may result from
excessive elongation of the spinal cord by curve correction or by ischemic injury of the anterior spinal
artery or its feeding radicular vessels, causing spinal cord ischemia.
Possible factors associated with higher risk of neurological complications of scoliosis surgery are
congenital scoliosis,scoliosis combined with hyperkyphosis, severity of the curve (Cobb angle over 90
degree),patients with congenital scoliosis,neuromuscular scoliosis, combined approach and decreased
spinal cord perfusion due to hypotension and haemorrhage.
The “ wake up” test was the first method to control the integrity of the motor tract in spinal surgery
but with many limitations. The “wake up” test gives only information of spinal cord function at a single
point in time, and the reversal of anesthesia confers other risks.
From the 1970s somatosensory evoked potential monitoring ( SEP) has been used and a large
multicenter survey by Nuwer in 1995 affirmed the efficacy of SEP monitoring in prevention of
neurologic deficits. Since SEPs only monitor the neural conduction through the dorsal columns, false
negative measurements happened and patients woke up paraplegic despite the absence of an
intraoperative SEP signal change.
In the 1990s Deletis , Epstein and colleagues introduced motoric transcranial electrical stimulation
monitoring ( MEP) to intramedullary spinal cord tumor surgery. MEP was soon adopted in scoliosis
surgery, and numerous studies have confirmed its efficacy.
MEP monitoring is more directly relevant for detecting motor pathway injury ,and MEP deterioration
often occurs before and sometimes, without SEP change ( Mac Donald et al 2007). Neverless, congruent
MEP/SEP deterioration increases diagnostic certainty and suggests a more severe transverse cord
compromise. In addition, reversible SEP deterioration without MEP change has been reported and
implies selective dorsal column compromise ( Tome-Bermejo et al 2014,Mac Donald 2007) There is a
critical window for intervention. Significant alteration of SEP and MEP signal, and recovery within 15
min. are usually not associated with postoperative deficits. ( Nuwer et al 2008).
The anesthesiologist and surgeons are able to intervente in a variety of ways when IOM raises warnings:
Elevating of the mean blood pressure to > 90mm Hg, increasing the oxygen concentration, measuring
arterial blood gas for metabolic abnormality or low hemoglobin, irrigating the wound with warm saline
solution, discontinuing spinal instrumentation,removing or adjusting grafts and hardware, and if the
evoked potentials fail to return,perform a wake up test.
There is general consensus in SEP intraoperative interpretation. A decrement in amplitude over 50 % is
used as a warning criterion. Over 10 % increment in latency is also used as a warning criterion, but
latency changes are quite common and less significant.
Different warning criteria have been proposed in MEP interpretation, ranging from changes in
thresholds that elicit muscle MEPs, amplitude variation, or simply the presence or absence of
responses. Presence of MEPs excludes paralysis, and disappearance is a strong predictor of new
weakness, with few false postives.
Disappearance is a major criterion, mandating restorative efforts. Marked amplitude reduction could
be a moderate criterion prompting restorative efforts, but may increase false positives. ( MacDonald
2014)
21
The D waves are generated by direct activation of the axon of fast conducting fibres of the corticospinal tract. Combined recording of D wave and muscle MEPs is a powerfull tool in spinal cord tumor
surgery .The D wave amplitude remaining above 50% of baseline appears to predict long-term recovery
of any early weakness, whereas irreversible over 50% reduction correlates with permanent motor
deficit. In scoliosis surgery the amplitude changes up to 70% ( Ulkatan et al.,2006). This might be due
to alterations of the distance between the spinal cord and the epidural recording electrode. Therfore,
there is no established criterion for scoliosis surgery. Because of the high incidence of false positive
results, the D wave is not very useful in IOM in scoliosis surgery.
To assess thoracic pedicle screw placement, testing of the pedicle screws may be performed. Triggered
thresholds below 6 mA should alert the surgeon to suspect a medial or inferior wall breach.
IOM does not eliminate all adverse neurologic events. Some neurological deficits can occur despite
interventions in response to the warning, because there is nothing that can be done, such as acute
anterior spinal artery thrombosis.
Monitoring only determines the spinal cord function at the moment of monitoring and delayed
postoperative paraplegia which is often correlated with hypotension, can occur many hours after
operation . Close postoperative observation is important.
Successful monitoring during scoliosis surgery requires good communication between the
neurophysiologist and the anesthesiologist. Neuromuscular blocking agents depress MEP and should not
be used. Inhalational anesthetics interfere particulary with MEPs and should be avoided. Total
intravenous anesthestics like propofol and opiate attenuate MEPs to a much lesser degree and should
be preferred.
It is recommened that the responsible person on the monitoring side should be an medical doctor with
subspecialty education in clinical neurophysiology and additional education on intraoperative
monitoring. ( Sutter et al 2007).
Reliance on computerized information, without validation by trained and experienced monitoring
professional can be dangerous. ( Yingling 2011)
Conclusion:
Optimal intraoperative monitoring during scoliosis surgery entails both SEP and MEP recording.
Combination of SEP and MEP monitoring provides assessment of entire spinal cord functionality in real
time.
There is strong evidence that multimodality intraoperative neuromonitorering is sensitive and specific
for detecting intraoperative neurologic injury during scoliosis surgery.
IOM is a valuable tool to optimization of outcome in scoliosis surgery. Multimodal IOM is the Gold
Standard in scoliosis surgery.
References
Nuwer MR.Intraoperative monitoring of neural function.Amsterdam:Elseviere;2008
Burke D,Nuwer MR;Daube J et al Intraoperative monitoring.The International Federation of Clinical
Neurophysiology.Electroenceph.Clin Neurophysiolo Suppl 52:133-148
Deletis V,Sala F.Intraoperative neurophysiological monitoring of the spinal cord during spinal cord
and spine surgery:a review focus on the corticospinal tracts.Clin Neurophysiol.2008;119(2):248-64
Diab M, Smith AR, Kuklo TR. The spinal Deformity Study Group et al Neural complications in the
surgical treatment of adolescent idiopathic scoliosis. Spine 2007;32:2759-2763
Delank KS,Delank HW,Kong DP et al.Iatrogenic paraplegia in spinal surgery.Arch Orthop Trauma
22
Surg 125:33-41
Mendriatta A,Emerson RG.Neurophysiologic intraoperative monitoring of scoliosis surgery.
J Clin.Neurophysiol 2009;26:62-69
Pastorelli F, Di Silvestre M, Plasmati R et al.The prevention of neural complications in the surgical
treatment of scoliosis: the role of the neurophysiological intraoperative monitoring. Eur Spine J
2011;20 (Suppl 1):105-114
Nuwer MR, Dawson EG, Carlon LG, et al. Somatosensory evoked potential spinal cord monitoring
reduces neurologic deficits after scoliosis surgery:results of a large multicenter survey.
Electroencephalogr Clin Neurophysiol 1995;96;1:6-11
Pelosi L, Lamb J, Grevitt M, et al. Combined monitoring of motor and somatosensory evoked
potentials in orthopaedic spinal surgery. Clin Neurophysiol 2002;113:1082-1091
MacDonald DB, Al Zayed Z. Stingsby B. Monitoring scoliosis surgery with combined multiple pulse
transcranial electric motor and cortical somatosensory evoked potentials from the lower and upper
extremities. Spine 2003;28:194-203
Schwartz DM, Auerbach JD, Dormans JP et al.
Neurphysiological detection of impending spinal cord injury during scoliosis surgery. J Bone Joint Surg
Am 2007 89 :2440-9.
Eggspühler A, Sutter M, Grob D et al.Multimodal intraoperative monitoring during surgery of spinal
deformities on 217 patients.Eur spine J 2007;(suppl):188-96
Sutter M, Deletis V, Dvorak J, et al. Current opinions and recommendations on multimodal
intraoperative monitoring during spine surgeries Eur Spine J16 2007; (Suppl 2):232-S237
Deletis V.Intraoperative neurophysiology and methodologies used to monitor the functional integrity of
the motor system.In:Deletis V,Shils JL,editors.Neurophysiology in neurosurgery.CA:Academic;2002:2551
Fehlings MG,Brodke DS,Norvell DC et al. The evidence for intraoperative neurophysiological
monitorering in spine surgery:does it make a different? Spine 2010;35:37-46
Szelenyi A,Kothbauer KF,Deletis V.Transcranial electric stimulation for intraoperative motor evoked
potential monitoring:Stimulation parameters and electrode montages:
Clin Neurophysiol.2007,118:1586-95
Balzer JR,Crammond D,Habeych M,et al.Intraoperative EMG during spinal pedicle screw
instrumentation,I:Intraoperative monitoring of neural function Handbook of Clinical
Neurophysiology:Elseviere,2008;Vol8:404-42
Devlin JD,Schwartz DM..Intraoperative neurophysiologic monitoring during spinal surgery
Jam Acad Orthop Surg 2007;15:549-560
Deletis V,Kothbauer K. Intraoperative Neurophysiology of the corticospinal tract
inE.Stalberg,H.S.Sharma and Y.Olsson (Eds),Spinal Cord monitoring.
Springer,Vienna,1998;421-444
Ginsburg HH,Shetter AG,Raudzens PA.Postoperative paraplegia with preserved intraoperative
somatosensory evoked potentials.J Neurosurg 1985;63:296-300
Jones SJ,Harrison R,Koh KF et al.Motor evoked potentials monitoring during spinal surgery:responses of
distal limb muscles to transcranial cortical stimulation with pulse trains.Elektroenceph Clin
Neurophysiol 1996;100:375-83
23
Kothbauer K,Deletis V,Epstein F.Motor evoked potential monitoring for intramedullary spinal cord
tumor surgery:correlation of clinical and neurophysiological data in a series of 100 consecutive
procedures.Neurosurg.Focus 1998;4(5):1-9
Ulkatan S,Neuwirth M,Bitan F et al.Monitoring of scoliosis surgery with epidurally recorded motor
evoked potentials ( D wave) revealed false results.Clin Neurophysiol.2006;2093-101
Tome-BermejoF,GarridoE,Glasby M et al.Rare true-positive isolated SSEP loss with preservation of MEPs
response during scoliosis correction.Spine 2014 ;39:60-3
Mac Donald DB,Zayed ZA,Saddiq A.Four-limb muscle motor evoked potential and optimized
somatosensory evoked potential monitoring with decussation assessment:results in 206 thoracolumbar
spine surgeries.Eur Spine 2007;16:171-187
Taylor BA,Webb PJ,Hetreed M et al.Delayed postoperative paraplegia with hypotension in adult revision
scoliosis surgery.Spine 1994;19(4):470-4
Yingling CD.Are there false-negative and false-positive motor-evoked potentials?
J Clin Neurophysiolo 2011,28:607-610
Sloan TO,Heyer EJ.Anesthesia for intraoperative neurophysiologic monitoring of the spinal cord.
J Neurosurg 96:430-443
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24
What can you see on Neuromuscular Imaging?
Michel Court-Payen, MD, PhD, Department of Musculoskeletal Radiology, GHP Gildhøj Private Hospital
Copenhagen, Brøndby, Denmark
Charlotte Denonville de la Cour, MD, Department of Neurophysiology, Rigshospitalet, University of
Copenhagen, Denmark
Ultrasound (US) is increasingly used for morphologic assessment of patients with nerve diseases as a
complement to neurophysiological examination. Compared to MRI, US has following advantages:
providing images with high resolution, multiregional (possible tracing of a long segment of a nerve,
detection of polyneuropathy), interactive (with the clinical examination), comparative (quick
examination of both sides), dynamic (nerve snapping at the elbow, US-guided needle aspiration or
injection, needle biopsy, placement of EMG-needle), minimal artifacts from metal. In contrary to US,
MRI provides visualization of nerves/muscles hidden by bony structures and detection of diffuse tissue
edema. MRI is also better to detect small deep-situated nerves, and gives a better overview of large
muscle groups.
The normal fascicular structure of nerves is well demonstrated on US. US can provide localization and
direct visualization of nerve entrapment with nerve flattening at the site of compression, proximal
(and sometimes distal) nerve swelling, nerve hyperemia (color Doppler examination). The cause of
nerve entrapment can be established (retinaculum, fibrous band, tenosynovitis, bone, osteosynthesis,
tumor, cyst, or anomalous muscle). Maximal nerve swelling can be measured (nerve area). Muscle
atrophy and/or fat degeneration, secondary to nerve entrapment, can be demonstrated and may be
the only finding in entrapment of very small nerves. Early muscle edema is not well demonstrated with
US, but easy to see on MRI.
US may also be useful in patients with blunt or open trauma for detection of nerve transsection,
neuroma and other lesions in the tendons and muscles. US may help detecting soft tissue tumors
compressing nerves, arising from nerves (schwanomas), or ganglion cysts invading nerves (peroneal or
tibial). MRI is required in patients with suspicion of malignancy.
US may have a role in primary myopathic disorders, neurogenic myopathies, inflammatory myopathies,
muscle tumors, and traumatic muscle lesions.
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25
Nerve and muscle ultrasound in neuromuscular disorders - Experiences and results of prospective
studies.
Erisela Qerama Montvilas, Department of Clinical Neurophysiology, Aarhus University Hospital, Denmark
This oral presentation will focus on an overview of studies on ultrasound in neuromuscular disorders
and will present cases, experiences and results of recent studies conducted in our department.
Since its first use in the 1950s for medical practice, ultrasound has become a sophisticated imaging
modality in the hands of specialists to diagnose a broad range of clinical disorders. Ultrasound provides
a fast real-time and dynamic imaging capability, less inconvenience for the patient and lower cost
compared to other imaging modalities. In the last two decades, ultrasound has taken an increasing
important place in the evaluation of neuromuscular disorders.
Studies on carpal tunnel syndrome (CTS) (1) and on ulnar nerve entrapment (UNE) (2) at the elbow have
shown that enlargement and loss of echogenicity are two consistent changes on ultrasound that can
distinguish diseased nerves from normal nerves. We have conducted a study on CTS and on UNE at the
elbow and will present some key results from those studies. Moreover, we bring cases and experiences
from the daily routine in our department where ultrasound is used as a supplement to the
electrodiagnostic tests.
Ultrasound may be more sensitive than EMG at detecting fasciculations (3,4) probably because it samples
a larger muscle region than needle EMG and is more tolerable than the EMG. We will present first results
of an ongoing study on ultrasound of muscles especially of the tounge in patients with various
neuromuscular disorders. Diseased muscle displays increased echogenicity and homogeneity, atrophy and
loss of the bone shadow (3). Electrographic ultrasound (EUS) is a dynamic strain imaging technique and
a promising technology to identify tissue stiffness. We will present results from an ongoing study on the
value of EUS as a diagnostic tool in muscle atrophy seen in neuromuscular diseases.
1-Sonography in the diagnosis of carpal tunnel syndrome: a critical review of the literature.
Beekman R, Visser LH Muscle Nerve. 2003;27(1):26
2- Ulnar neuropathy at the elbow: follow-up and prognostic factors determining outcome.
Beekman R, Wokke JH, Schoemaker MC, Lee ML, Visser LH Neurology. 2004;63(9):1675.
3- Muscle ultrasound in neuromuscular disorders. Pillen S, Arts IM, Zwarts MJ Muscle Nerve. 2008;37(6):679
4-Ultrasonographic detection of fasciculations markedly increases diagnostic sensitivity of ALS.
Misawa S, Noto Y, Shibuya K, Isose S, Sekiguchi Y, Nasu S, Kuwabara S
Neurology. 2011 Oct;77(16):1532-7. Epub 2011 Sep 21.
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26
Experiences of combined electrophysiology and High Resolution Ultrasound in the examination of
peripheral nerves
Nils Wolfram, MD, Department of Clinical Neurophysiology, Rigshospitalet, Glostrup
([email protected])
Janus Kaufmann Lindqvist, MD, Department of Neurology, Rigshospitalet, Blegdamsvej
([email protected])
A large amount of all patients referred to EMG/ENG examination of peripheral nerves end up with an
unspecified diagnosis. Furthermore, electrophysiological findings do not always fit with the patients’
medical history and/or clinical examination.
To evaluate the extent to which High Resolution Ultrasound (HRUS) is contributive or non-contributive
to electrophysiology in relation to final diagnosis, examinations combining electrophysiology and HRUS
in 2014 were evaluated.
HRUS was used as an investigative tool when:
- medical history and/or clinical examination gave suspicion of other specific peripheral nerve injury as
expected from electrophysiological findings alone (e.g. scar tissue, trauma, tumor) or
- medical history and/or clinical examination gave suspicion of localized peripheral nerve injury despite
normal or unspecified electrophysiological findings.
HRUS findings were classified in different groups whether supplemental ultrasound was contributive or
non-contributive to electrophysiology in relation to the final diagnosis.
HRUS is able to contribute to electrophysiological examination in order to localize or reveal further
information in peripheral nerve injury.
A couple of examples will be shown in the lecture. BACK TO PROGRAM
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27
Brain basis of social interaction
Riitta Hari, Department of Neuroscience and Biomedical Engineering, Aalto University, Finland
[email protected]
Human social interaction is everywhere, effectively shaping our brains and minds. Although social
interaction is among the most complex functions humans (and their brains) perform, the interaction
often appears surprisingly easy. I will advocate the view that to fully understand human brain function
we ultimately should be able to study interacting people in naturalistic conditions and to collect
information from two brains at the same time, ending up in “two-person neuroscience” (2PN). This
approach goes beyond the commonly applied “spectator science” that assumes that humans (and their
brains) are reactive and that even complex social functions can be probed by presenting complexenough stimuli that the subject just observes. However, in reality people are actively participating
interactors who by their behavior dynamically affect the (social) stimuli they will receive at the next
moment.
I will discuss our approaches and challenges in imaging of single brains under naturalistic conditions and
in imaging two brains at the same time (”hyperscanning”). For 2PN purposes, we have built a setup for
simultaneous MEG-to-MEG recordings between two distant laboratories and a 2-coil fMRI for imaging
two subjects in the same magnet. Analysis of the 2PN-data is still extremely challenging. Most likely, we
have not yet adopted the best experimental setups.
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28
REM sleep Behavior Disorder: an early sleep disease marker for later neurodegeneration
Poul J. Jennum, Professor, chief consultant, DMSci. Danish Center for Sleep Medicine, Department of
Clinical Neurophysiology and Faculty of Health, University of Copenhagen. Glostrup Hospital, Denmark
Parkinson’s disease and other alpha-synucleinopathies are some of the most disabling, mortal and
common chronic and neurodegenerative disorders that affect middle age and elderly humans. Once
fully developed there is only symptomatic treatment but no treatment which affect the serious disease
course. Therefore early detection of alpha-synucleinopathy is imperative for potential disease
modifying treatment.
Idiopathic Rapid eye movement sleep Behavior Disorder (iRBD) has recently been identified as a strong
and early risk factor for later development of an alpha-syn’s with a conversion rate of more than 80% in
10 years. In addition, 60-100% of alpha-synucleinopathy patients suffer from RBD. iRBD is a parasomnia,
characterized by loss of the normal REM sleep skeletal muscle atonia, resulting in motor/behavioral
activity during sleep in relation to dream mentation. Therefore iRBD may be an early marker in the
preclinical/premotor phase for alpha-synucleinopathies which is confirmed in neuropathological studies
early identification of iRBD, increased understanding of disease mechanisms and development of
sensitive diagnostic measures is central for future treatment-options, neuroprotective strategies, and
preventing or postponing that patients with iRBD will develop Parkinson’s disease or other alphasynucleinopathies.
We have shown that specific electrophysiological polysomnographic markers characterize RBD and PD
patients, including: changes in macro sleep structure (loss of wake-sleep stability, sleep transitions),
sleep microstructure (e.g. sleep spindles, K-complexes), muscle tone, eye activity and autonomic
activity. Further we have found that changes in sleep pattern are diagnostic for diagnosing RBD/PD as
compared to controls.
These findings may be important for identification of early phases of RBD/PD, understanding disease
process, monitoring disease progression and improving diagnostic methods. Further the results may
raise opportunity to identify candidates for disease intervention.
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Electromyographic activity in REM sleep Behaviour Disorder.
Rune Frandsen
Objectives Rapid eye movement (REM) sleep behaviour disorder (RBD) is characterised by dream
enactment and REM sleep without atonia. The evaluation of atonia is based on visual criteria but there
is a need for more objective, quantitative measurements. We aimed establish a method for
determining the baseline and all other parameters in automatic quantifying submental motor activity
during REM sleep.
Method Analysis of electromyographic (EMG) activity of the submental muscle in polysomnographs of 35 patients
with idiopathic RBD (iRBD), 31 controls and 43 Parkinson's patients. Six adjustable parameters for motor activity
were defined. EMG activity was automatically detected and quantified. 648 possible combinations of parameters
defining EMG activity was compared for the ability to separate RBD patients from controls. After identification of
the optimal method for separating RBD from controls, the parameters were used for PD patients.
Results Automatic baseline estimation improved characterisation of atonia during REM sleep. We found an
optimised method for quantifying motor activity during REM sleep. The method was stable in iRBD and PD patients
and can be used to differentiate RBD from controls with a sensitivity and specificity of 83%.
Conclusion We developed and applied a sensitive, quantitative, automatic algorithm to evaluate loss of atonia in
RBD patients.
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30
Prepulse inhibition is associated with attention, processing speed, and 123I-FP-CIT SPECT in
Parkinson's disease.
Zoetmulder M1, Biernat HB2, Nikolic M3, Korbo L2, Friberg L4, Jennum PJ5.
Department of Neurology, Bispebjerg University Hospital, Copenhagen NV, Denmark Danish Center for
Sleep Medicine, Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup, Denmark.
1
2
Department of Neurology, Bispebjerg University Hospital, Copenhagen NV, Denmark.
3
Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup, Denmark.
Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen
NV, Denmark.
4
Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup,
Denmark.
5
BACKGROUND:
Prepulse inhibition is a measure of sensorimotor gating, which reflects the ability to filter or 'gate'
irrelevant information. Prepulse inhibition is dramatically altered in basal ganglia disorders associated with
dysfunction in the midbrain dopaminergic system, and corresponding cognitive information processing
deficits such as slowed processing speed. Parkinson's disease is characterised by the degeneration of
the midbrain dopaminergic system and is associated with cognitive dysfunction, including slowed
information processing. Although sensorimotor processes in Parkinson's disease have been extensively
studied in relation to motor function, less is known about the potential role of sensorimotor processes in
cognitive function.
OBJECTIVE:
We investigated the relationship between prepulse inhibition, cognition and nigrostriatal dysfunction, as
measured with 123I-FP-CIT-SPECT scanning, in patients with Parkinson's disease.
METHODS:
38 Parkinson patients were assessed with prepulse inhibition, neuropsychological tests, and neurological
investigation. A subset of these patients underwent 123I-FP-CIT-SPECT scanning.
RESULTS:
Patients with a higher level of prepulse inhibition performed better on cognitive measures tapping
attention and processing speed than patients with a lower level of prepulse inhibition. Furthermore, there
were significant correlations between prepulse inhibition and 123I-FP-CIT uptake in the striatum.
CONCLUSIONS:
Our results suggest that the level of prepulse inhibition is related to the efficiency of information
processing in Parkinson's disease, and to the density of dopamine transporters in the striatum.
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31
Sleep stability and transitions in patients with idiopathic REM sleep behavior disorder and patients
with Parkinson's disease
Julie, Christensen - Denmark - [email protected]
Objective: Patients w ith idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) are at high
risk of developing Parkinson's disease (PD). As wake/sleep-regulation is thought to involve neurons
located in the brainstem and hypothalamic areas, we hypothesize that the neurodegeneration in iRBD/PD
is likely to affect wake/sleep and REM/non-REM (NREM) sleep transitions. Methods: We determined the
frequency of wake/sleep and REM/NREM sleep transitions and the stability of wake (W), REM and NREM
sleep as measured by polysomnography (PSG) in 27 patients with PD, 23 patients with iRBD, 25 patients
with periodic leg movement disorder (PLMD) and 23 controls. PD patients were divided in those with RBD
and those without, and iRBD patients were divided in those with major self -reported dream enactments
and those with minor. Measures were computed based on manual scorings and data-driven labeled sleep
staging. Results: Measures computed rom the data-driven labeling showed significant differences.
Patients with PD showed significantly lower REM stability than controls and patients with PLMD. Patients
with iRBD had significantly lower REM stability compared with controls. Patients with PD and RBD
showed significantly lower NREM stability and significantly more REM/NREM transitions than controls. No
significant differences were found between PD with and without RBD, and between iRBD patients with
and without major self -reported dream-enactments. The measures computed from the manual scorings
lacked to show any significant differences. Conclusion: We conclude that W, NREM and REM stability
and transitions are progressively affected in iRBD and PD, probably reflecting the successive involvement
of brain stem areas from early on in the disease. Sleep stability and transitions determined by a datadriven approach could support the evaluation of iRBD and PD patients.
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The Copenhagen Longitudinal Study of Male Cognitive Aging and fMRI and EEG measures of
cognitive decline
SubTitle: fMRI, EEG and cognition
Martin, Lauritzen - Denmark - [email protected]
The Copenhagen Longitudinal Study of Male Cognitive Aging (CoLoSMA) explores how aging influences
cognition and brain function in testpersons from the Metropolit 1953 Danish male birth cohort. CoLoSMA
is a longitudinal study based on repeated IQ tests, and the selection of the study population is based on
each person's IQ trajectory. The aim is to identify etiological factors for cognitive decline in otherw ise
healthy males, and to obtain fMRI and EEG data that can be used to substantiate a decline in cognitive
function in order to be able to intervene before dementia sets in. Higher cognitive functions in mammals,
such as perception and cognition, are critically dependent on synchronized neocortical network activity,
especially activity in the gamma range (30 – 100 Hz), which is produced by repeated discharges of fastspiking inhibitory interneurons that synchronize the activity of numerous pyramidal cells by rhythmic
inhibition. The presentation will describe the design of the CoLoSMA study, review the literature on
neocortical gamma oscillations in pre-MCI/MCI (MCI= mild cognitive impairment) patients, and present
the data obtained so far with fMRI in this birth cohort. The fMRI data point to a disturbance in one of the
brain's functional connectivity networks in a large group of males (n=100) with subclinical cognitive
decline in late midlife. The alterations are similar to the pattern seen in patients with Alzheimer's disease
and MCI, which suggests that physiological correlates of cognitive decline may be discovered by use of
appropriate methodologies. We now seek
to substantiate the abnormalities at the neuronal network level by examining evoked neocortical gamma
oscillations as described in the following 2 presentations. Inclusion of test-persons from the Metropolit
cohort in the EEG studies was initiated February 1, 2015 and data from these males are not included in
the following talks that describes results from normal controls.
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Selective attention modulates auditory and visual steady state responses
Krisztina, Benedek - Denmark - [email protected]
Steady state evoked potentials (EP) are widely used in cognitive neuroscience and may be useful as
predictors of cognitive decline. Cognition may be examined as rivalry for attention between two sensory
stimuli. Rivalry entails competitive interactions at multiple neural sites in higher brain areas, and may
provide insights into the neural bases of awareness and attention. This study examined the power
spectrum of auditory steady state responses in the presence of a competing visual task. Steady state
auditory or visual EPs were recorded in 15 healthy individuals in three consecutive stimulation paradigms
that were presented in randomized order. First, the power of an auditory 45 Hz, amplitude-modulated (2
Hz carrier frequency) stimulation was assessed without competing inputs. Second, a visual image of a
face/vase illusion was presented alternating with a grey background at a frequency range of 36 Hz. Third,
the auditory and visual stimulations were presented together without special instruction as to which one to
attend to. The response at the stimulus f requency w as normalized to the response within the
surrounding frequencies, and SNRs and power of the evoked responses w ere measured and compared.
The results demonstrate that the auditory cortical responses at 45 Hz w ere markedly decreased by a
competing visual stimulus. In comparison, rivalry for attention obtained by presentation of the complex,
visuo-auditory paradigm resulted in a 3 fold increase of the power of the visual stimulation at 36 Hz.
Auditory evoked responses were localised around, centro-temporal and centro-frontal areas, while the
peak of the 36 Hz frequency elicited visual response was localised above the parieto-occipital cortex. Our
findings indicate that without a goal directed attention the competition between auditory and visual
processing is mainly driven by the visual stimulus during a complex sensory input. The low gamma
activity evoked by this paradigm will be applied to study the
test-persons in the study of cognitive decline.
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Neurophysiological correlates of illusions: Visual perceptive network study
Anna Horwitz, Nelly Richard, Krisztina Benedek, Keng Wah Pang, Miki Nikolic, Martin Lauritzen.
Steady state visual evoked potentials (SSVEP) have been used widely in cognitive neuroscience, but the
extent to which SSVEPs can be used to track cognitive function is unknown. The amplitude of the SSVEP
response is enhanced in response to attention, working memory and in several other cognitive processes.
The strongest local source of SSVEPs is located in the striate cortex and propagates by the combined
activity of locally and broadly distributed sources to secondary visual cortical areas. The aim of the study
was to assess variations in the SSVEPs during a visual task where the participants were shown a vaseface illusion interchanging with a grey background with a flickering rate of 2 Hz, 8Hz and 36 Hz, and the
evoked activity patterns for the vase-face illusion was compared with the power and spatial distribution
elicited by simple checkerboard stimulation with alternations at the same three frequencies. Our study
included 20 healthy individuals, mean age 35 years. Signal to noise ratios, and EEG power of the
equivalent frequencies were calculated and compared statistically between checkerboard stimulation and
the complex vase-face illusory image. SSVEP amplitudes were 3-5 times larger for the complex visual
task as compared to checkerboard stimulation. The localization of the maximum power of the SSVEP
response varied for different stimulation frequencies: 8 Hz stimulation elicited a response with maximum
corresponding to the striate cortex, while the amplitude maximum at 36 Hz stimulation frequency was
measured above the subdominant parieto-occipital areas. Different areas of activation of SSVEP during
various stimulation points out the involvement of higher level cognitive processing during perception of
illusory images, and higher stimulation frequencies elicits activity in association cortex known to be
involved in cognitive processing. We suggest that SSVEP recordings may be useful to track changes in
cognitive function.
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Neocortical gamma oscillations in epilepsy
Krisztina Benedek, Martin Lauritzen
Neocortical gamma oscillations emerge from the precise synaptic interactions of excitatory pyramidal cells
and fast spiking inhibitory interneurons, which release GABA at high rate. This presentation compares
high frequency EEG activity preceding and during ictal recording of patients with idiopathic generalized
epilepsy and frontal lobe seizures.
We used power spectral analyses of the EEG and calculated the time-frequency cross-coherence
measures of neocortical gamma oscillations to search for interictal and ictal interregional rhythmic
synchrony preceding and complementing clinical seizures. During primarily generalized seizures an
abrupt rise of all frequencies was seen synchronously over both hemispheres. The rise in EEG gamma
oscillations was short-lasting and decreased before activity at lower frequency ranges. Although interictal
gamma activity was significantly higher in this population compared to non-epileptic patient’s recordings
no changes were observed prior or after their clinical event. On the contrary in cases of frontal lobe
epilepsy a gradual increase of high beta and gamma band was observed prior to their clinical event. This
high frequency increase coincided with a decrease of delta activity.
Our data supports the hypothesis that gamma synchrony plays a key role in generating and maintaining a
seizure. The increase in gamma oscillatory activity precedes clinical seizures in focal epilepsy, while it
rises simultaneously with other frequencies during generalized seizures.
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